CVE-2021-36191: Fortinet FortiWeb

Medium severity, CVSS 5.4. EPSS: 0.5% chance of exploitation in the next 30 days.

A url redirection to untrusted site ('open redirect') in Fortinet FortiWeb version 6.4.1 and below, 6.3.15 and below allows attacker to use the device as proxy via crafted GET parameters in requests to error handlers

Affected products

• Fortinet FortiWeb: from 6.0.0, up to and including 6.0.7; from 6.2.0, up to and including 6.2.6; from 6.3.0, up to and including 6.3.15; version 6.1.0 only; version 6.1.1 only; version 6.1.2 only; …

Published 2021-12-08. Last modified 2026-06-17.